Mobile communication system, mobile communication method, mobile station, and exchange

ABSTRACT

An object of the present invention is to avoid congestion, by restricting only processing which causes the congestion without affecting processing which essentially should not be restricted. In a mobile communication system according to the present invention, an exchange MSC/SGSN includes: a congestion factor detector configured to detect a congestion occurrence factor in the switching exchange MSC/SGSN, and a restriction indication transmitter configured to transmit, a restriction indication, to a radio network controller, based on the detected congestion occurrence factor, the restriction indication instructing a processing type that should be restricted in the switching exchange MSC/SGSN congestion occurrence factor. The radio network controller RNC is provided with a broadcast information transmitter configured to transmit broadcast information including the received restriction indication to a mobile station UE.

CROSS REFERENCE TO RELATED APPLICATION

This application is based upon and claims the benefit of priority fromthe prior Japanese Patent Application No. P 2006-277014, filed on Oct.10, 2006; the entire contents of which are incorporated herein byreference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a mobile communication system, a mobilecommunication method, a mobile station, and an exchange.

2. Description of the Related Art

In conventional mobile communication systems, for example, all mobilestations of passengers on a train start transmission of a locationregistration request at the same time when the train crosses over fromone location registration area to another location registration area,which causes a problem that overloads for processing are imposed onradio capacity and an exchange.

In addition, there is also another problem that when a large amount ofcalling processing is performed at the same time for a specific event(for example, application for a TV program or the like), thetransmission of calling requests for performing the calling processingcauses overloads for processing on a radio capacity and an exchange.

To solve these problems, current 3GPP specifications define “DomainSpecific Access Control (hereinafter referred to as DSAC)”. Inaccordance with the DSAC, a mobile communication system is configured toseparately restrict processing in a circuit switch and processing in apacket switch if congestion is caused in a network.

Note that a mobile communication system to which the DSAC is not appliedis configured to restrict (prohibit) all the processing in a circuitswitch and a packet switch when congestion is caused in a circuitswitched network or a packet switched network. Accordingly, a mobilestation cannot perform calling/call-receiving processing and locationregistration processing through either the circuit switch or the packetswitch.

In addition, a mobile communication system to which the DSAC is appliedhas a configuration in which, when congestion is caused in a circuitswitched network or a packet switched network, all the processing isprohibited in a domain having the congestion caused, that is, in anexchange (a circuit switch or a packet switch) in the network having thecongestion caused. Thus, the mobile station cannot performcalling/call-receiving processing and location registration processingthrough the exchange (the circuit switching exchange or the packetswitching exchange) in the network having the congestion caused.

Referring to FIGS. 1 to 3, the description will be given of an operationto restrict processing performed in each exchange in a mobilecommunication system to which a conventional DSAC is applied.

As shown in FIGS. 1 to 3, at step S1000, a circuit switching exchangeMSC or a packet switching exchange SGSN detects congestion caused in acircuit switched network or a packet switched network.

At step S1001, the exchange detecting the congestion (the circuitswitching exchange MSC or the packet switching exchange SGSN) transmits,to the radio network controller RNC, “a CS restriction indication” or “aPS restriction indication” for instructing to restrict all theprocessing in the circuit switching exchange MSC or the packet switchingexchange SGSN.

At step S1002, the radio network controller RNC creates broadcastinformation including the received CS restriction indication or the PSrestriction indication. At step S1003, the radio network controller RNCtransmits the created broadcast information through a radio base stationBTS to a location registration area belonging to the radio networkcontroller RNC.

As a result, the mobile station cannot perform thecalling/call-receiving processing and the location registrationprocessing through the exchange (the circuit switching exchange or thepacket switching exchange) in the network in which congestion is caused.

[Non-patent Document 1] 3GPP TS.24.008 V6.1.2.0 (6.c.0), issued in March2006

[Non-patent Document 2] 3GPP TS.25.331 V6.5.0, issued in March 2005

In general, a main factor of congestion in a network is specificprocessing like location registration processing, calling processing,and the like. Thus, in many cases, it is sufficient to restrict onlysome of such processing in an exchange, that is, it is not necessary torestrict all the processing in the exchange.

However, a mobile communication system to which the conventionalaforementioned DSAC is applied is configured to restrict all theprocessing in a circuit switch or a packet switch for all mobilestations that belong to a specific location registration area. For thisreason, there is a problem that such unnecessarily-prohibitive restrictaffects call-receiving processing of a mobile station in the area, whichprocessing essentially should not be restricted, or locationregistration processing by a mobile station which moves to the specificlocation registration area.

SUMMARY OF THE INVENTION

The present invention has been made in view of the forgoing problems.Accordingly, it is an object of the present invention to provide amobile communication system, a mobile communication method, a mobilestation and an exchange, which are capable of avoiding congestion byrestricting only processing causing the congestion without affectingprocessing that essentially should not be restricted.

A first aspect of the present invention is summarized as a mobilecommunication system including a radio network controller and anexchange, wherein the exchange includes a congestion factor detectorconfigured to detect a congestion occurrence factor showing a processingwhich causes a congestion to occur in the exchange, and; a restrictionindication transmitter configured to transmit a restriction indicationper the processing, to the radio network controller based on thedetected congestion occurrence factor, the restriction indicationinstructing a type of the processing which should be restricted in theexchange and, the radio network controller comprises: a broadcastinformation transmitter configured to transmit, to a mobile station,broadcast information including the received restriction indication.

In the first aspect, the exchange is any one of a circuit switchingexchange and a packet switching exchange

In the first aspect, the type of the processing shows at least one oflocation registration processing and calling processing.

A second aspect of the present invention is summarized as a mobilecommunication method for performing mobile communications through aradio network controller and an exchange, including: detecting, at theexchange, a congestion occurrence factor showing a processing whichcauses a congestion to occur in the exchange; transmitting, at theexchange, a restriction indication per the processing, to the radionetwork controller based on the detected congestion occurrence factor,the restriction indication instructing a type of the processing whichshould be restricted in the exchange; transmitting, at the radio networkcontroller, to a mobile station, broadcast information including thereceived restriction indication; and restricting, at the mobile station,processing corresponding to the restriction indication included in thereceived broadcast information.

A third aspect of the present invention is summarized as a mobilestation configured to perform mobile communications through a radionetwork controller and an exchange, including: a broadcast informationreceiver configured to receive broadcast information transmitted fromthe radio network controller; an analyzer configured to analyze aspecific processing in a specific exchange to be restricted on the basisof a restriction indication per the processing, included in the receivedbroadcast information; and a processor configured to restrict thespecific processing in the analyzed specific exchange.

A forth aspect of the present invention is summarized as an exchangeused in a mobile communication system, including; a congestion factordetector configured to detect a congestion occurrence factor showing aprocessing which causes a congestion to occur in the exchange; and arestriction indication transmitter configured to transmit, a restrictionindication, to a radio network controller in the mobile communicationsystem based on the detected congestion occurrence factor, therestriction indication instructing a type of the processing which shouldbe restricted in the exchange.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a diagram illustrating an operation when CS restrict or PSrestrict is performed in a conventional mobile communication system;

FIG. 2 is a sequential diagram showing an operation when the CS restrictis performed in the conventional mobile communication system;

FIG. 3 is a sequential diagram showing an operation when the PS restrictis performed in the conventional mobile communication system;

FIG. 4 is a functional block diagram of an exchange according to a firstembodiment of the present invention;

FIG. 5 is a functional block diagram of a radio network controlleraccording to the first embodiment of the present invention;

FIG. 6 is a diagram showing one example of restrict information to bereceived in the radio network controller according to the firstembodiment of the present invention;

FIG. 7 is a diagram showing one example of restrict information to bereceived in the radio network controller according to the firstembodiment of the present invention;

FIG. 8 is a diagram showing one example of restrict information to bereceived in the radio network controller according to the firstembodiment of the present invention;

FIG. 9 is a diagram showing one example of restrict information to bereceived in the radio network controller according to the firstembodiment of the present invention;

FIG. 10 is a diagram showing one example of restrict information to bereceived in the radio network controller according to the firstembodiment of the present invention;

FIG. 11 is a functional block diagram of a mobile station according tothe first embodiment of the present invention;

FIG. 12 is a diagram illustrating an operation when CS locationregistration restrict is performed in a mobile communication systemaccording to the first embodiment of the present invention;

FIG. 13 is a sequential diagram showing an operation when the CSlocation registration restrict is performed in the mobile communicationsystem according to the first embodiment of the present invention;

FIG. 14 is a diagram illustrating an operation when PS locationregistration restrict is performed in the mobile communication systemaccording to the first embodiment of the present invention;

FIG. 15 is a sequential diagram showing an operation when the PSlocation registration restrict is performed in the mobile communicationsystem according to the first embodiment of the present invention;

FIG. 16 is a diagram illustrating an operation when CS calling restrictis performed in the mobile communication system according to the firstembodiment of the present invention;

FIG. 17 is a sequential diagram showing an operation when the CS callingrestrict is performed in the mobile communication system according tothe first embodiment of the present invention;

FIG. 18 is a sequential diagram showing operations when the CS callingrestrict and the CS location registration restrict are performed in themobile communication system according to the first embodiment of thepresent invention;

FIG. 19 is a sequential diagram showing operations when the CS callingrestrict and the PS location registration restrict are performed in themobile communication system according to the first embodiment of thepresent invention; and

FIG. 20 is a sequential diagram sowing an operation when the CS locationregistration restrict is cancelled in the mobile communication systemaccording to the first embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION Configuration of a MobileCommunication System According to the First Embodiment of the PresentInvention

The configuration of a mobile communication system according to a firstembodiment of the present invention will be described below by referringto FIGS. 4 to 12.

As shown in FIG. 12, the mobile communication system according to thepresent embodiment is provided with an exchange (a circuit switchingexchange MSC or a packet switching exchange SGSN), a radio networkcontroller RNC, a plurality of base stations BS#A and BS#B and aplurality of mobile stations UE#1 and UE#2.

The circuit switching exchange MSC is a device responsible for circuitswitched services and is configured to perform location registrationprocessing for a circuit switched network of a mobile station UE and toperform communication restrict in the circuit switched network.

In addition, the packet switching exchange SGSN is a device responsiblefor packet switched services and is configured to perform locationregistration processing for a packet switched network of the mobilestation UE and to perform communication restrict in the packet switchednetwork.

As shown in FIG. 4, the switching exchange MSC or SGSN is provided witha congestion factor detector 11 and a restriction indication transmitter12.

The congestion factor detector 11 is configured to detect a congestionoccurrence factor showing a processing which causes a congestion tooccur in the switching exchange MSC or SGSN.

Specifically, the congestion factor detector 11 is configured to detectwhich processing caused congestion to occur in the switching exchangeMSC or SGSN.

For example, the congestion factor detector 11 may be configured todetect a occurrence of congestion based on a CPU usage. For example, ifa process with a CPU usage being higher than a predetermined threshold(for example, a location registration process or a calling process) isdetected, the congestion factor detector 11 determines that this processcaused congestion to occur.

Note that the congestion factor detector 11 may be configured to detectcongestion is caused by a single congestion factor or may be configuredto detect congestion is caused by a plurality of factors.

The restriction indication transmitter 12 is configured to transmit, tothe radio network controller RNC, a restriction indication per theprocessing for instructing a type of processing (for example, locationregistration processing or calling processing) which should berestricted in the switching exchange MSC or SGSN, based on thecongestion occurrence factor detected by the congestion factor detector11.

For example, if the restriction indication transmitter 12 detects aprocess with a CPU usage higher than a predetermined threshold (forexample, a location registration process or a calling process), therestriction indication transmitter 12 may be configured to transmit arestriction indication (for example, a location registration restrictionindication or a calling restriction indication) for instructing torestrict corresponding processing (for example, location registrationprocessing or calling processing) on the mobile station UE side.

Note that the restriction indication transmitter 12 may be configured totransmit a restriction indication for restricting single processing ormay be configured to transmit a restriction indication for restricting aplurality of processing.

The radio network controller RNC is a device responsible for performingprocessing of radio communication control with the mobile stations UE.

In addition, the radio network controller RNC is configured to exchangepredetermined information with the mobile station UE through a radionetwork and is configured to notify the switching exchange MSC/SGSN ofthe predetermined information exchanged with the mobile station UE.

As shown in FIG. 5, the radio network controller RNC is provided with arestriction indication receiver 21 and a broadcast informationtransmitter 22.

The restriction indication receiver 21 is configured to receive arestriction indication transmitted from the switching exchange MSC/SGSN.

The broadcast information transmitter 22 is configured to createbroadcast information including the restriction indication received bythe restriction indication receiver 21 to transmit the information tothe mobile station UE.

Here, the broadcast information transmitter 22 is configured toseparately create and transmit broadcast information for the circuitswitched network and broadcast information for the packet switchednetwork.

Note that the broadcast information transmitter 22 may create andtransmit broadcast information for restricting one processing or maycreate and transmit broadcast information for restricting a plurality ofprocessing.

FIG. 6 shows one example of broadcast information created by thebroadcast information transmitter 22.

As shown in FIG. 7, broadcast information used in a conventional mobilecommunication system is configured so that “SIB3 (System InformationBlock Type 3)” defined by 3GPP would include a normal restrictionindication, a CS restriction indication, and a PS restrictionindication.

In contrast, as shown in FIGS. 8 to 10, the mobile communication systemaccording to the present invention is configured so that the broadcastinformation transmitter 22 adds a restriction indication (a locationregistration restriction indication, an originating restrictionindication, or the like) to “SIB3” and broadcast them to a plurality ofmobiles stations UE.

Specifically, as shown in FIG. 8, the broadcast information transmitter22 may be configured to add information elements showing restrictionindications such as a location registration restriction indication, acalling restriction indication, a call-receiving restriction indication,and the like to “SIB3” and to define “presence or absence of a CSrestrict (true or false)” and “present or absent of a PS restrict (trueor false)” for each of the information elements.

For example, if the Cs restrict is “true”, the location registrationrestriction indication is “true”, and the restriction indication otherthan these is “false”, the mobile station UE can determined that “onlythe location registration processing in the circuit switching exchangeMSC is restricted”.

In addition, as shown in FIG. 9, the broadcast information transmitter22 may be configured to add information elements showing restrictionindications respectively to the information element showing the CSrestriction indication and the information element showing the PSrestriction indication in the “SIB3” and to define “presence or absenceof a location registration restrict”, “presence or absence of a callingrestrict”, “presence or absence of a call-receiving restrict” and thelike respectively in the information elements showing the addedrestriction indications.

For example, if the location registration processing in the circuitswitching exchange MSC and the calling processing in the packetswitching exchange SGSN are restricted, “Access class” in theinformation element showing the Cs restriction indication is “true”, andonly “the location registration restriction indication” in theinformation element showing the restriction indication in theinformation element showing the CS restriction indication is “true”,“Access class” in the information element showing the PS restrictionindication is “true”, and only “the calling restriction indication” inthe information element showing the restriction indication in theinformation element showing the PS restriction indication is “true”.

In addition, as shown in FIG. 10, the broadcast information transmitter22 may be configured to add an information element showing a restrictionindication separately from the information element showing the CSrestriction indication and the information element showing the PSrestriction indication in “SIB3” and to define “presence or absence of alocation registration restrict”, “presence or absence of a callingrestrict”, “presence or absence of a call-receiving restrict”, and thelike in each of the information elements showing the added restrictionindications.

According to the example of FIG. 10, the broadcast informationtransmitter 22 can define “presence or absence of a locationregistration restrict”, “presence or absence of a calling restrict”,“presence or absence of a call-receiving restrict”, and the likeregardless of “the presence or absence of the CS restrict” and “thepresence or absence of the PS restrict”.

For example, even if both of the CS restrict and the PS restrict are“false”, the mobile station US is restricted in the processing that theinformation element showing a restriction indication is “true”.

Note that the broadcast information transmitter 22 may be configured tocreate and transmit broadcast information including a restrictionindication if congestion is caused in the radio capacity.

As shown in FIG. 11, the mobile station UE is provided with a broadcastinformation receiver 31, an analyzer 32, a location registrationprocessor 33, a calling processor 34, and a call-receiving processor 35.

The broadcast information receiver 31 is configured to receive broadcastinformation transmitted from the radio network controller RNC.

The analyzer 32 is configured to analyze specific processing in thespecific exchange (the circuit switching exchange MSC or the packetswitching exchange SGSN) to be restricted based on the restrictionindication included in the broadcast information received by thebroadcast information receiver 31 (see, FIG. 6).

The location registration processor 33, the calling processor 34, andthe call-receiving processor 35 are configured to suppress the specificprocessing in the specific exchange (the circuit switching exchange MSCor the packet switching exchange SGSN) analyzed by the analyzer 32.

Specifically, the location registration processor 33 is configured totransmit a Cs location registration request or a PS locationregistration request to the circuit switching exchange MSC or the packetswitching exchange SGSN to perform location registration processing.

In addition, the location registration processor 33 is configured tosuppress the location registration processing in the specific exchange(the circuit switching exchange MSC or the packet switching exchangeSGSN) analyzed by the analyzer 32.

Specifically, the calling processor 34 is configured to perform callingprocessing by transmitting a CS calling request or a PS calling requestto the circuit switching exchange MSC or the packet switching exchangeSGSN.

In addition, the calling processor 34 is configured to suppress callingprocessing in the specific exchange (the circuit switching exchange MSCor the packet switching exchange SGSN) analyzed by the analyzer 32.

Specifically, the call-receiving processor 35 is configured to performcall-receiving processing by receiving a CS call-receiving notificationor a PS call-receiving notification from the circuit switching exchangeMSC or the packet switching exchange SGSN.

In addition, the call-receiving processor 35 is configured to suppresscall-receiving processing in the specific exchange (the circuitswitching exchange MSC or the packet switching exchange SGSN) analyzedby the analyzer 32.

Operation of the Mobile Communication System According to the FirstEmbodiment of the Present Invention

By referring to FIGS. 11 to 20, the operation of the mobilecommunication system according to the first embodiment of the presentinvention will be described. Note that in examples of FIGS. 11 to 20, abase station BS only transfers information, and the description thereofwill be omitted.

Firstly, by referring to FIGS. 12 to 14, the description will be givenof an operation which is performed in a case where a CS locationregistration restrict or a PS location registration restrict isperformed in the mobile communication system according to the presentembodiment.

If a train moves from a location registration area A to a locationregistration area B at step S100, mobile stations UE#1 of users on thetrain transmit location registration requests (CS location registrationrequests, PS location registration requests, or CS/PS locationregistration requests) at the same time, in the location registrationarea B at step S101.

At step S102, an exchange (a circuit switching exchange MSC or a packetswitching exchange SGSN) receives a large amount of locationregistration requests, which causes congestion.

At step S103, the switching exchange MSC or SGSN transmits, to a radionetwork controller RNC, a location registration restriction indication(a CS location registration restriction indication or a PS locationregistration restriction indication) for restricting locationregistration processing in the exchange.

At step S104, the radio network controller RNC creates broadcastinformation including the received location registration restrictionindication, and at step S105 transmits the created broadcast informationthrough broadcast to the location registration area B.

At step S106, by receiving and analyzing the broadcast information, themobile station UE#1 recognizes that the location registration processingis restricted in the location registration area B and suppresses thelocation registration processing in the location registration area B.

Note that even in such a case, since a mobile station UE#2 which alreadybelongs to the location registration area B has already performed thelocation registration processing, the mobile station UE#2 can performcalling and call-receiving processing.

In particular, in a boundary of a location registration area along arail road, the radio network controller RNC continuously transmitsbroadcast information including the location registration restrictionindication (note that a restrict rate is changed in operation) toprevent the location registration processing from being performed at thesame time, so that the above-mentioned congestion can be prevented.

Secondly, by referring to FIGS. 15 to 17, the description will be givenof an operation which is performed in a case where Cs calling restrictor PS calling restrict is performed in the mobile communication systemaccording to the present invention.

At step S201, mobile stations US transmit calling requests (CS callingrequests (for example, voice call origination requests or TV callorigination requests)) or PS calling requests (for example, i-mode(registered trade mark) connection requests or mail transmissionrequests) at the same time on the occasion of a specific event.

At step S202, the exchange (the circuit switching exchange MSC or thepacket switching exchange SGSN) receives a large amount of callingrequests, which causes congestion.

At step S203, the switching exchange MSC or SGSN transmits, to the radionetwork controller RNC, a calling restriction indication (a CS callingrestriction indication or a PS calling restriction indication) forrestricting calling processing in the exchange.

At step S204, the radio network controller RNC creates broadcastinformation including the received calling restriction indication, andat step S205, transmits the created broadcast information throughbroadcast to a specific area.

At step S206, by receiving and analyzing the broadcast information, themobile station UE recognizes that the calling processing is restrictedin the specific area and suppresses the calling processing in thespecific area.

Thirdly, by referring to FIG. 18, the description will be given of anoperation which is performed in a case where a CS calling restrict and aCS location registration restrict is performed in the mobilecommunication system according to the present embodiment.

At step S301, a plurality of mobile stations UE transmit CS callingrequests, and at step S302 transmit CS location registration requests.

At step S303, the circuit switching exchange MSC receives a large amountof the CS calling requests and the CS location registration requests,which causes congestion.

At step S304, the circuit switching exchange MSC transmits, to the radionetwork controller RNC, a CS calling restriction indication and a CSlocation registration restriction indication for restricting CS callingprocessing and CS location registration processing in the circuitswitching exchange MSC.

At step S305, the radio network controller RNC creates broadcastinformation including the received CS calling restriction indication andCS location registration restriction indication, and at step S306transmits the created broadcast information through broadcast to aspecific area.

At step S307, by receiving and analyzing the broadcast information, themobile station UE recognizes that the CS calling processing and the CSlocation registration processing are restricted in the specific area andsuppresses the Cs calling processing and the CS location registrationprocessing in the specific area.

Fourthly, by referring to FIG. 19, the description will be given of anoperation which is performed in a case where Cs calling restrict and PSlocation registration restrict are performed in the mobile communicationsystem according to the present embodiment.

At step S401, a plurality of mobile stations UE transmit Cs callingrequests, and at step S402 transmit PS location registration requests.

At step S403, the circuit switching exchange MSC receives a large amountof the CS calling requests, which causes congestion.

At step S404, the circuit switching exchange MSC transmits, to the radionetwork controller RNC, CS calling restriction indication forrestricting the Cs calling processing in the circuit switching exchangeMSC.

In addition, at step S405, the packet switching exchange SGSN receives alarge amount of the PS location registration requests, which causescongestion.

At step 6406, the packet switching exchange SGSN transmits, to the radionetwork controller RNC, a PS location registration restrictionindication for restricting the PS location registration processing inthe packet switching exchange SGSN.

At step S407, the radio network controller RNC creates broadcastinformation including the received CS calling restriction indication andPS location registration restriction indication, and at step S408transmits the created broadcast information through broadcast to aspecific area.

At step S409, by receiving and analyzing the broadcast information, themobile station UE recognizes that the CS calling processing and the PSlocation registration processing are restricted in the specific area andsuppresses the CS calling processing and the PS location registrationprocessing in the specific area.

Fifthly, by referring to FIG. 20, the description will be given of anoperation which is performed in a case where CS location registrationrestrict is cancelled.

At step S501, the radio network controller RNC creates broadcastinformation including a CS location registration restriction indicationand transmits the created broadcast information as “SYSTEM INFORMATION”through broadcast.

At step S502, by receiving and analyzing the broadcast information, themobile station UE which has moved to the specific area recognizes thatthe CS location registration is restricted in the specific area andsuppresses the CS location registration in the specific area.

At step S503, the mobile station UE uses “Routing Area Update Request(update type: RA updating)” to transmit a PS location registrationrequest to the packet switching exchange SGSN in the specific area.

At step S504, the mobile station UE receives, from the packet switchingexchange SGSN, “Routing Area Update Accept (update result: RA updated)”notifying that the PS location registration processing is completed inthe specific area.

At step S505, the circuit switching exchange MSC transmits, to the radionetwork controller RNC, a CS location registration restrict cancellationinstruction for instructing to cancel the restrict of the CS locationregistration processing in the specific area.

At step S506, the radio network controller RNC creates broadcastinformation including the received CS location registration restrictcancellation instruction, and at step S507 transmits “Paging Type 1(bcch modify)”, and thereafter at step S508 transmits the createdbroadcast information as “SYSTEM INFORMATION” through broadcast to thespecific area.

At step S509, by receiving and analyzing the broadcast information, themobile station UE recognizes that the restrict of the locationregistration processing is cancelled in the specific area.

At step S510, the mobile station UE uses “Routing Area Update Request(update type: combined RA LA updating with IMSI attach)” to transmit aCS location registration request to the packet switching exchange SGSNin the specific area.

At step S511, the packet switching exchange SGSN transmits, to thecircuit switching exchange MSC, a CS location registration request forthe mobile station UE in response to the received “Routing Area UpdateRequest (update type: combined RA·LA updating with IMSI attach)”.

At step S512, the packet switching exchange SGSN transmits to the mobilestation UE “Routing Area Update Accept (update result: combined RA/LAupdated)” that is a notification of completion of the CS locationregistration processing in the specific area.

Advantageous Effects of the Mobile Communication System According to theFirst Embodiment of the Present Invention

According to the mobile communication system according to the firstembodiment of the present invention, the restriction indicationtransmitter 12 of the switching exchange MSC or SGSN specifies andrestricts the processing which causes congestion in each exchange, sothat an adverse effect on the processing that should not be restrictedcan be avoided.

In addition, according to the mobile communication system according tothe first embodiment of the present embodiment, the restrictionindication transmitter 12 of the switching exchange MSC or SGSNcontinuously transmits restriction indications in a specific place (suchas a boundary of a location registration area on a rail road) in orderto restrict specific processing (location registration processing) inthe specific place in advance, so that a state of congestion can beavoided.

1. A mobile communication system including a radio network controllerand an exchange, wherein the exchange comprises: a congestion factordetector configured to detect a congestion occurrence factor showing aprocessing which causes a congestion to occur in the exchange, and; arestriction indication transmitter configured to transmit a restrictionindication per the processing, to the radio network controller based onthe detected congestion occurrence factor, the restriction indicationinstructing a type of the processing which should be restricted in theexchange and, the radio network controller comprises: a broadcastinformation transmitter configured to transmit, to a mobile station,broadcast information including the received restriction indication. 2.The mobile communication system according to claim 1, wherein theexchange is any one of a circuit switching exchange and a packetswitching exchange.
 3. The mobile communication system according toclaim 1, wherein the type of the processing shows at least one oflocation registration processing and calling processing.
 4. A mobilecommunication method for performing mobile communications through aradio network controller and an exchange, comprising: detecting, at theexchange, a congestion occurrence factor showing a processing whichcauses a congestion to occur in the exchange; transmitting, at theexchange, a restriction indication per the processing, to the radionetwork controller based on the detected congestion occurrence factor,the restriction indication instructing a type of the processing whichshould be restricted in the exchange; transmitting, at the radio networkcontroller, to a mobile station, broadcast information including thereceived restriction indication; and restricting, at the mobile station,processing corresponding to the restriction indication included in thereceived broadcast information.
 5. A mobile station configured toperform mobile communications through a radio network controller and anexchange, comprising: a broadcast information receiver configured toreceive broadcast information transmitted from the radio networkcontroller; an analyzer configured to analyze a specific processing in aspecific exchange to be restricted on the basis of a restrictionindication per the processing, included in the received broadcastinformation; and a processor configured to restrict the specificprocessing in the analyzed specific exchange.
 6. An exchange used in amobile communication system, comprising: a congestion factor detectorconfigured to detect a congestion occurrence factor showing a processingwhich causes a congestion to occur in the exchange; and a restrictionindication transmitter configured to transmit, a restriction indication,to a radio network controller in the mobile communication system basedon the detected congestion occurrence factor, the restriction indicationinstructing a type of the processing which should be restricted in theexchange.